Events on Thursday, May 10th, 2012

Abstract: Our ability to control electronic properties at semiconductor interfaces has had enormous scientific and technological implications. Extending this idea beyond the familiar semiconductors, one can now construct thin films of artificial "quantum" materials with atomic layer precision. With these new systems lies the promise of taking advantage of their strong quantum many-body interactions at interfaces or with dimensionality to control their electronic and magnetic properties. This is a new frontier in condensed matter physics, but to fully understand what happens in these artificial quantum materials, one requires advanced tools for both spectroscopy and synthesis. To achieve this, we have developed a new approach which combines oxide molecular beam epitaxy (MBE) with high-resolution angle-resolved photoemission spectroscopy (ARPES). As one example, I will describe our work on digital manganite superlattices ([LaMnO3]2n / [SrMnO3]n), comprised of alternating LaMnO3 and SrMnO3 blocks. Our ARPES measurements reveal that by controlling the separation between the LaMnO3-SrMnO3 interfaces, we can drive the interfacial quasiparticle states from 3D ferromagnetic metal, to a 2D polaron liquid, and finally to a pseudogapped ferromagnetic insulator. I will also describe some of our work on thin films of the elusive "infinite layer" cuprate Sr1-xLaxCuO2, which we can stabilize epitaxially, thus allowing us to address fundamental issues regarding the asymmetry between doping electrons and holes in the high-Tc cuprates.